Electric switch mechanism



Nov. 29, 1932'.

F. 1.. COOK ELECTRIC SWITCH MECHANISM Filed April 5; 1931 INVENTOR lzxderc/v Leonard Cook 6 s PC N R O T T A Patented Nov. 29,1932

., uN Tco s'rA'rEs PATENT, OFFICE nnnc'rnrc swrrcn Encnamsm Application med April}, 1981, Serial No.

The invention relates to improvements. in electric switch mechanism, and the objects of my improvements are first, to provide quick make and quick break mechanism; sec- 5 ond, to simplify the construction of the switch mechanism and the manufacture of its parts;

third, to reduce the number of parts which it is necessary to assemble together in the manufacture oi the switch; and fourth, to pro- 10 vide mechanism which is readily assembled,

mrong, compact, durable, and possessed of relatively great rigidity.

In the drawing:

Fig. l is a plan view of a switch, ports oi 15 which are shown in disassembled position;

Fig. 2 is an elevation of the assembled switch;

Fig. 3 is section on the line 3-4 of Fig. 2, end

Fig. 4 is c diagrammatic representation or? the nosition of s. fulcrum. i

The base member 1 which forms the body of the switch is moulded in one piece out of m "materiel such as bakelite, and is shaped to accommodate metal terminals 2 which are secured in position by swaging, riveting or burn ing, and are provided with strong metal contect strips 3 which are formed to give en elficient spring contact with a roller 4 which 39 functions as a movable contact-making member. Additional recesses 5 enable the terminals and contact strips to be duplicated so as to provide a two-way switch if desired. Gounter-sunk holes '6 are provided to accomdate screws by which the body of the switch. may be secured in position on the wall or other supggrt. A curved track 7 is provided in the dy of the switch which is provided with a guide ridge 8 adapted to be straddled by the grooved roller 4 having a centre groove 9 which accommodates the bi-- forested end of a flat pressure member 10, the stem of which asses up into a compression 5 rin 11 and into a central hole in the cyw lindrical stem of an anti-torsicnspear-head 12, the point of which is pivoted in a conical recess 13 inside a rocking member 14', formed of Bakelite or like material, which has two 5 depending arms 15 provided with ofiset fulcrnm pins 1% adapted to be sprung into pivot inated.

the switch at a point below, and preferably 527,571, and. in Australia April 17, 1930.

sdckcts 17 formed in the body of the switch. The pressure member, spring and spear-head together form an expansible thrust member from which. obviously torsion has been elim- 55 The contact-making member is thus car ried along a track by an expsnsible thrust member pivoted to a rocking member, and, when the switch is viewed in its upright pe sition as shown, the fulcrum l6 should be positioned on a line drawn downwards in radial direction through the middle point of the track and should be below the lowest position of the point of the sneer-heed 12. This will be appreciated more clearly by considering the diagrammatic i epresentetlon shown in Figure in which the rocker is shown pass ing through the middle point of its swing, and in which e linefio fitl is shown drown downwardly in radial direction from the apex of the conical recess 13 and through the middle point oi the track. it is obvious that it the movement of the contact-maker is to be properly balanced the fulcrum 16 must be positioned on the vertical centre line 2 5- 7 2G. The fulcrum 16 is also positioned below the lowest position of the point or the speor head. The position of the fulcrum along this line may be varied within reasonable limits,

as will be obvious to a mechanic, and the fulcrum might even be positioned below the track. The centre or centres of curvature of the track, except at its ends, should be positioned above the top of the line'26%.

The pivoting of this telescopic thrust member at a ooint inside the top of the rocking member and the pivoting of the fulcrum pins of the rocking member to the body of considerably below, the top of the rocking 99 member provides a very compact construction and this construction also possesses the great advantage that the stress on'the telescopic thrust member is lon "tudi'nal, forcing the contact-making mem r downwardly against the track and the s ear -head upwar ly into the recess in the roc no; member without any alnpreciable bending or tors onal stresses. he construction is exceedingly v so simple, strong snd'durable end possesses re- 1 markably few separate parts. Furthermore, these separate parts are of simple construction and can be assembled exceedingly quickly. The bearing points of the offset fulcrum pins of the rocking member being wide apart give exceptional rigidity to the structure apart from the desired swinging movement of the switch. The rapidity of action may be increased by providing a ridge 18 across the track at one or both ends so that the umpover is delayed appreciably during the initial movement of the rocking member and the consequent extra compression of the spring causes the final movement of the contact-making member to be all the more rapid. When the rocking member is swung over, one of the shoulders 19 of the pressure member may be" adapted to press against one of the shoulders 20 of the guide ridge of the track and the roller is thus prised over the ridge 18. To limit the movement of the roller gradually and thus promote silent action the curvature of the track increases rapidly near its ends.

A screw thread 21 is provided on the outer portion of the base member and is adapted to engage a screw thread 22 on' the inside periphery of the widest portion of the cover 23. It has been customary in the past to provide a screw thread on or adjacent to the edge of the aperture through which the knob 24 of.

the rocking member protrudes and as a result the thread is often stripped owing to the excessive leverage which can be obtained when the cover is grasped at its outer edge. The present construction prevents this excessive leverage being thus exerted and provides a very eflicient means of attaching the cover to the switch. 1

The moulding of the body 1 of the switch is facilitated by forming. the pivot-sockets 17 as inverted U-shaped slots with rounded tops and open at the bottom. The downward movement of the rocking member is prevented, not merely by the spring 11, but by a bearing surface 25 positioned beneath each arm 15.

The switch has been described as if it'were upright, but obviously it will be inverted for use on a ceiling or in like position.

I claim:

1. The combination, in an electric switch, of a base member, a rocking member, a fulcrum rockably connectingsaid rocking member to said base member, an expansible thrust .member on said rocking member and also being situated on a line drawn radially through the middle point of said track.

3. The combination in an electric switch, of a base member, a rocking member, a fulcrum rockably connecting said rocking member to said base member, an expansible thrust member pivoted to said rocking member, an insulated track on said base member, the curvature of said track increasing rapidly near its ends, a contact-making member carried along said track by said thrust member, said fulcrum of said rocking member being situated below the lowest position of the pivot poim of said thrust member on said rocking member and also being situated on a line drawn radially through the middle point of said track.

4. The combination, in an electric switch,

of a base member, a rocking member, a fulcrum rockably CODIIGCtiIlg said rocking member to said base member, an expansible thrust member pivoted to said rocking member, an

insulated track on said base member, a contact-making member carried along said track by said thrust member, the point at which said thrust member is pivoted to said rocking member being more remote from the contact making member than the fulcrum of the rocking memberis.

5. In electric switch mechanism, a base 'member moulded out of insulating material such as bakelite; a rocking member moulded out of simllar material, arms depending from said rocking member, said arms being sprung into rockable connection with said base mem- In witness whereof, the said FREDERICK LEONARD CooK, has hereunto set his hand this fifth day of March, 1931.

' FREDERICK LEONARD COOK.

member pivoted to said rocking member, an

insulated track on said base member, a contact-makingmember carried along said track by said thrust member, said fulcrum of said rocking member bein situated below the lowest position of the p1vot point of said thrust member on said rocking member and also being situated'on a line drawn radially through the middle point of said track.

2. The combination, in an electric switch, of a base member, a rocking member, a ful- 

